1/*
2 * This program is free software; you can redistribute it and/or
3 * modify it under the terms of the GNU General Public License version 2
4 * as published by the Free Software Foundation; or, when distributed
5 * separately from the Linux kernel or incorporated into other
6 * software packages, subject to the following license:
7 *
8 * Permission is hereby granted, free of charge, to any person obtaining a copy
9 * of this source file (the "Software"), to deal in the Software without
10 * restriction, including without limitation the rights to use, copy, modify,
11 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
12 * and to permit persons to whom the Software is furnished to do so, subject to
13 * the following conditions:
14 *
15 * The above copyright notice and this permission notice shall be included in
16 * all copies or substantial portions of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
21 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
23 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
24 * IN THE SOFTWARE.
25 */
26
27#ifndef __XEN_BLKIF__BACKEND__COMMON_H__
28#define __XEN_BLKIF__BACKEND__COMMON_H__
29
30#include <linux/module.h>
31#include <linux/interrupt.h>
32#include <linux/slab.h>
33#include <linux/blkdev.h>
34#include <linux/vmalloc.h>
35#include <linux/wait.h>
36#include <linux/io.h>
37#include <linux/rbtree.h>
38#include <asm/setup.h>
39#include <asm/hypervisor.h>
40#include <xen/grant_table.h>
41#include <xen/page.h>
42#include <xen/xenbus.h>
43#include <xen/interface/io/ring.h>
44#include <xen/interface/io/blkif.h>
45#include <xen/interface/io/protocols.h>
46
47extern unsigned int xen_blkif_max_ring_order;
48extern unsigned int xenblk_max_queues;
49/*
50 * This is the maximum number of segments that would be allowed in indirect
51 * requests. This value will also be passed to the frontend.
52 */
53#define MAX_INDIRECT_SEGMENTS 256
54
55/*
56 * Xen use 4K pages. The guest may use different page size (4K or 64K)
57 * Number of Xen pages per segment
58 */
59#define XEN_PAGES_PER_SEGMENT (PAGE_SIZE / XEN_PAGE_SIZE)
60
61#define XEN_PAGES_PER_INDIRECT_FRAME \
62 (XEN_PAGE_SIZE/sizeof(struct blkif_request_segment))
63#define SEGS_PER_INDIRECT_FRAME \
64 (XEN_PAGES_PER_INDIRECT_FRAME / XEN_PAGES_PER_SEGMENT)
65
66#define MAX_INDIRECT_PAGES \
67 ((MAX_INDIRECT_SEGMENTS + SEGS_PER_INDIRECT_FRAME - 1)/SEGS_PER_INDIRECT_FRAME)
68#define INDIRECT_PAGES(_segs) DIV_ROUND_UP(_segs, XEN_PAGES_PER_INDIRECT_FRAME)
69
70/* Not a real protocol. Used to generate ring structs which contain
71 * the elements common to all protocols only. This way we get a
72 * compiler-checkable way to use common struct elements, so we can
73 * avoid using switch(protocol) in a number of places. */
74struct blkif_common_request {
75 char dummy;
76};
77
78/* i386 protocol version */
79
80struct blkif_x86_32_request_rw {
81 uint8_t nr_segments; /* number of segments */
82 blkif_vdev_t handle; /* only for read/write requests */
83 uint64_t id; /* private guest value, echoed in resp */
84 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
85 struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
86} __attribute__((__packed__));
87
88struct blkif_x86_32_request_discard {
89 uint8_t flag; /* BLKIF_DISCARD_SECURE or zero */
90 blkif_vdev_t _pad1; /* was "handle" for read/write requests */
91 uint64_t id; /* private guest value, echoed in resp */
92 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
93 uint64_t nr_sectors;
94} __attribute__((__packed__));
95
96struct blkif_x86_32_request_other {
97 uint8_t _pad1;
98 blkif_vdev_t _pad2;
99 uint64_t id; /* private guest value, echoed in resp */
100} __attribute__((__packed__));
101
102struct blkif_x86_32_request_indirect {
103 uint8_t indirect_op;
104 uint16_t nr_segments;
105 uint64_t id;
106 blkif_sector_t sector_number;
107 blkif_vdev_t handle;
108 uint16_t _pad1;
109 grant_ref_t indirect_grefs[BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST];
110 /*
111 * The maximum number of indirect segments (and pages) that will
112 * be used is determined by MAX_INDIRECT_SEGMENTS, this value
113 * is also exported to the guest (via xenstore
114 * feature-max-indirect-segments entry), so the frontend knows how
115 * many indirect segments the backend supports.
116 */
117 uint64_t _pad2; /* make it 64 byte aligned */
118} __attribute__((__packed__));
119
120struct blkif_x86_32_request {
121 uint8_t operation; /* BLKIF_OP_??? */
122 union {
123 struct blkif_x86_32_request_rw rw;
124 struct blkif_x86_32_request_discard discard;
125 struct blkif_x86_32_request_other other;
126 struct blkif_x86_32_request_indirect indirect;
127 } u;
128} __attribute__((__packed__));
129
130/* x86_64 protocol version */
131
132struct blkif_x86_64_request_rw {
133 uint8_t nr_segments; /* number of segments */
134 blkif_vdev_t handle; /* only for read/write requests */
135 uint32_t _pad1; /* offsetof(blkif_request..,u.rw.id)==8 */
136 uint64_t id;
137 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
138 struct blkif_request_segment seg[BLKIF_MAX_SEGMENTS_PER_REQUEST];
139} __attribute__((__packed__));
140
141struct blkif_x86_64_request_discard {
142 uint8_t flag; /* BLKIF_DISCARD_SECURE or zero */
143 blkif_vdev_t _pad1; /* was "handle" for read/write requests */
144 uint32_t _pad2; /* offsetof(blkif_..,u.discard.id)==8 */
145 uint64_t id;
146 blkif_sector_t sector_number;/* start sector idx on disk (r/w only) */
147 uint64_t nr_sectors;
148} __attribute__((__packed__));
149
150struct blkif_x86_64_request_other {
151 uint8_t _pad1;
152 blkif_vdev_t _pad2;
153 uint32_t _pad3; /* offsetof(blkif_..,u.discard.id)==8 */
154 uint64_t id; /* private guest value, echoed in resp */
155} __attribute__((__packed__));
156
157struct blkif_x86_64_request_indirect {
158 uint8_t indirect_op;
159 uint16_t nr_segments;
160 uint32_t _pad1; /* offsetof(blkif_..,u.indirect.id)==8 */
161 uint64_t id;
162 blkif_sector_t sector_number;
163 blkif_vdev_t handle;
164 uint16_t _pad2;
165 grant_ref_t indirect_grefs[BLKIF_MAX_INDIRECT_PAGES_PER_REQUEST];
166 /*
167 * The maximum number of indirect segments (and pages) that will
168 * be used is determined by MAX_INDIRECT_SEGMENTS, this value
169 * is also exported to the guest (via xenstore
170 * feature-max-indirect-segments entry), so the frontend knows how
171 * many indirect segments the backend supports.
172 */
173 uint32_t _pad3; /* make it 64 byte aligned */
174} __attribute__((__packed__));
175
176struct blkif_x86_64_request {
177 uint8_t operation; /* BLKIF_OP_??? */
178 union {
179 struct blkif_x86_64_request_rw rw;
180 struct blkif_x86_64_request_discard discard;
181 struct blkif_x86_64_request_other other;
182 struct blkif_x86_64_request_indirect indirect;
183 } u;
184} __attribute__((__packed__));
185
186DEFINE_RING_TYPES(blkif_common, struct blkif_common_request,
187 struct blkif_response);
188DEFINE_RING_TYPES(blkif_x86_32, struct blkif_x86_32_request,
189 struct blkif_response __packed);
190DEFINE_RING_TYPES(blkif_x86_64, struct blkif_x86_64_request,
191 struct blkif_response);
192
193union blkif_back_rings {
194 struct blkif_back_ring native;
195 struct blkif_common_back_ring common;
196 struct blkif_x86_32_back_ring x86_32;
197 struct blkif_x86_64_back_ring x86_64;
198};
199
200enum blkif_protocol {
201 BLKIF_PROTOCOL_NATIVE = 1,
202 BLKIF_PROTOCOL_X86_32 = 2,
203 BLKIF_PROTOCOL_X86_64 = 3,
204};
205
206/*
207 * Default protocol if the frontend doesn't specify one.
208 */
209#ifdef CONFIG_X86
210# define BLKIF_PROTOCOL_DEFAULT BLKIF_PROTOCOL_X86_32
211#else
212# define BLKIF_PROTOCOL_DEFAULT BLKIF_PROTOCOL_NATIVE
213#endif
214
215struct xen_vbd {
216 /* What the domain refers to this vbd as. */
217 blkif_vdev_t handle;
218 /* Non-zero -> read-only */
219 unsigned char readonly;
220 /* VDISK_xxx */
221 unsigned char type;
222 /* phys device that this vbd maps to. */
223 u32 pdevice;
224 struct file *bdev_file;
225 /* Cached size parameter. */
226 sector_t size;
227 unsigned int flush_support:1;
228 unsigned int discard_secure:1;
229 /* Connect-time cached feature_persistent parameter value */
230 unsigned int feature_gnt_persistent_parm:1;
231 /* Persistent grants feature negotiation result */
232 unsigned int feature_gnt_persistent:1;
233 unsigned int overflow_max_grants:1;
234};
235
236struct backend_info;
237
238/* Number of requests that we can fit in a ring */
239#define XEN_BLKIF_REQS_PER_PAGE 32
240
241struct persistent_gnt {
242 struct page *page;
243 grant_ref_t gnt;
244 grant_handle_t handle;
245 unsigned long last_used;
246 bool active;
247 struct rb_node node;
248 struct list_head remove_node;
249};
250
251/* Per-ring information. */
252struct xen_blkif_ring {
253 /* Physical parameters of the comms window. */
254 unsigned int irq;
255 union blkif_back_rings blk_rings;
256 void *blk_ring;
257 /* Private fields. */
258 spinlock_t blk_ring_lock;
259
260 wait_queue_head_t wq;
261 atomic_t inflight;
262 bool active;
263 /* One thread per blkif ring. */
264 struct task_struct *xenblkd;
265 unsigned int waiting_reqs;
266
267 /* List of all 'pending_req' available */
268 struct list_head pending_free;
269 /* And its spinlock. */
270 spinlock_t pending_free_lock;
271 wait_queue_head_t pending_free_wq;
272
273 /* Tree to store persistent grants. */
274 struct rb_root persistent_gnts;
275 unsigned int persistent_gnt_c;
276 atomic_t persistent_gnt_in_use;
277 unsigned long next_lru;
278
279 /* Statistics. */
280 unsigned long st_print;
281 unsigned long long st_rd_req;
282 unsigned long long st_wr_req;
283 unsigned long long st_oo_req;
284 unsigned long long st_f_req;
285 unsigned long long st_ds_req;
286 unsigned long long st_rd_sect;
287 unsigned long long st_wr_sect;
288
289 /* Used by the kworker that offload work from the persistent purge. */
290 struct list_head persistent_purge_list;
291 struct work_struct persistent_purge_work;
292
293 /* Buffer of free pages to map grant refs. */
294 struct gnttab_page_cache free_pages;
295
296 struct work_struct free_work;
297 /* Thread shutdown wait queue. */
298 wait_queue_head_t shutdown_wq;
299 struct xen_blkif *blkif;
300};
301
302struct xen_blkif {
303 /* Unique identifier for this interface. */
304 domid_t domid;
305 unsigned int handle;
306 /* Comms information. */
307 enum blkif_protocol blk_protocol;
308 /* The VBD attached to this interface. */
309 struct xen_vbd vbd;
310 /* Back pointer to the backend_info. */
311 struct backend_info *be;
312 atomic_t refcnt;
313 /* for barrier (drain) requests */
314 struct completion drain_complete;
315 atomic_t drain;
316
317 struct work_struct free_work;
318 unsigned int nr_ring_pages;
319 bool multi_ref;
320 /* All rings for this device. */
321 struct xen_blkif_ring *rings;
322 unsigned int nr_rings;
323 unsigned long buffer_squeeze_end;
324};
325
326struct seg_buf {
327 unsigned long offset;
328 unsigned int nsec;
329};
330
331struct grant_page {
332 struct page *page;
333 struct persistent_gnt *persistent_gnt;
334 grant_handle_t handle;
335 grant_ref_t gref;
336};
337
338/*
339 * Each outstanding request that we've passed to the lower device layers has a
340 * 'pending_req' allocated to it. Each buffer_head that completes decrements
341 * the pendcnt towards zero. When it hits zero, the specified domain has a
342 * response queued for it, with the saved 'id' passed back.
343 */
344struct pending_req {
345 struct xen_blkif_ring *ring;
346 u64 id;
347 int nr_segs;
348 atomic_t pendcnt;
349 unsigned short operation;
350 int status;
351 struct list_head free_list;
352 struct grant_page *segments[MAX_INDIRECT_SEGMENTS];
353 /* Indirect descriptors */
354 struct grant_page *indirect_pages[MAX_INDIRECT_PAGES];
355 struct seg_buf seg[MAX_INDIRECT_SEGMENTS];
356 struct bio *biolist[MAX_INDIRECT_SEGMENTS];
357 struct gnttab_unmap_grant_ref unmap[MAX_INDIRECT_SEGMENTS];
358 struct page *unmap_pages[MAX_INDIRECT_SEGMENTS];
359 struct gntab_unmap_queue_data gnttab_unmap_data;
360};
361
362
363#define vbd_sz(_v) bdev_nr_sectors(file_bdev((_v)->bdev_file))
364
365#define xen_blkif_get(_b) (atomic_inc(&(_b)->refcnt))
366#define xen_blkif_put(_b) \
367 do { \
368 if (atomic_dec_and_test(&(_b)->refcnt)) \
369 schedule_work(&(_b)->free_work);\
370 } while (0)
371
372struct phys_req {
373 unsigned short dev;
374 blkif_sector_t nr_sects;
375 struct block_device *bdev;
376 blkif_sector_t sector_number;
377};
378
379int xen_blkif_interface_init(void);
380void xen_blkif_interface_fini(void);
381
382int xen_blkif_xenbus_init(void);
383void xen_blkif_xenbus_fini(void);
384
385irqreturn_t xen_blkif_be_int(int irq, void *dev_id);
386int xen_blkif_schedule(void *arg);
387void xen_blkbk_free_caches(struct xen_blkif_ring *ring);
388
389int xen_blkbk_flush_diskcache(struct xenbus_transaction xbt,
390 struct backend_info *be, int state);
391
392int xen_blkbk_barrier(struct xenbus_transaction xbt,
393 struct backend_info *be, int state);
394struct xenbus_device *xen_blkbk_xenbus(struct backend_info *be);
395void xen_blkbk_unmap_purged_grants(struct work_struct *work);
396
397#endif /* __XEN_BLKIF__BACKEND__COMMON_H__ */
398

source code of linux/drivers/block/xen-blkback/common.h